In the modren atomic model it could be best said that electrons are usually ?
a. moving in defined orbits
b. locked into distinct shells
c. constantly moving between shells
d. moving in a unpredictable patterns within their shell

Hello, the answer would be D.

This is because electrons, while able to be found in the shell, cannot mathematically be pinpoint to an exact location. Heisenberg's Uncertainty principle requires both uncertainty of momentum and uncertainty of position are non-zero values, which is impossible to detect with electron movement.